The present invention relates to an information memory apparatus and in particular to a memory apparatus suitable for storing information in a three-dimensional form.
Devices which handle digital information such as images and voices have made rapid advances in performance improvement. In keeping therewith, information memory apparatuses have also made great advances. As representative information memory apparatuses, there are semiconductor memories, hard disks and optical disks. They are basically obtained by arranging information storing elements in a two-dimensional form. Higher integration and lower cost of them have been made mainly relying upon advance of the microprocessing technology. However, it has also become gradually difficult to make the processing technology micro. It is said that promoting higher integration and lower costs rapidly as in the past is not easy hereafter.
It is conceivable to arrange memory elements not in a two-dimensional form but in a three-dimensional form, as means for solving this problem. Its example is described in the following papers.
A multilayer waveguide type read only memory card obtained by stacking planar optical waveguides as multiple layers is described in JP-A-11-337756.
A memory apparatus which uses cylindrical glass or plastics as a memory medium and reads information by using the computer tomography technology is described in JP-A-06-076374.
Details concerning the principle of the computer tomography technology are described in Digital Picture Processing, Second Edition, Volume 1, Azriel Rosenfeld and Avinash C. Kak, Academic Press Inc., Chapter 8, pp. 353 to 430.
A shape of a memory medium obtained by rolling a sheetlike medium into a cylindrical shape is shown in FIG. 6 in JP-A-2006-31894.